Plumbing and drainage

Common problems include low hot water pressure, leaking drains, and corrosion of original pipes.

Original details

Water supply

Public piped water supplies were generally available in New Zealand from the 1880s. Where a water supply was not available, such as in rural areas, rainwater storage tanks provided the household water.

Original plumbing pipes were galvanised steel and occasionally copper piping. PVC and polybutylene did not become available until the 1960s.

Water heating

Until the 1930s, water was commonly heated using a wetback system connected to a solid-fuel coal range. Chip-heaters, which had a water jacket around the fire box, were also used to produce hot water for bathroom and kitchen use. 

A gas califont or ‘geyser’, located in the kitchen above the sink or in the bathroom above the bath, used the same approach as the chip heater with a water jacket around the burning gas.

In the laundry, a built-in, fuel-fired copper boiler was used for clothes washing.

Though electric water heaters were available from about 1915, they did not start to become widespread until the 1930s when homes started to get wiring capable of carrying the necessary load.

Stormwater and sewage

By the 1920s, most larger communities had comprehensive public sewer systems. Bungalows typically had 4” (100 mm) pipes, made of earthenware or cast iron, that connected to the sewer system. Where there was no sewer system, the drains would run into a septic tank system.

Early sewer mains were terracotta or cast iron pipes, typically ranging in size from 9–15” (225–375 mm) in diameter. 

Original stormwater and sewage drains were often combined, but any systems that were originally combined should have been separated long ago.

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If a bathroom or kitchen has been upgraded, it is likely that re-plumbing has also been carried out, and original steel or copper plumbing pipes will most likely have been replaced by PVC or polybutylene.

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Common problems and remedies 

Galvanised steel pipes

If there is any original galvanised steel piping left it is likely to be in poor condition due to internal corrosion restricting water flow through the pipes.

Black plastic pipes

During the late 1970s and early 1980s, a particular type of black plastic pipe was installed into new homes as well as retrofitted into existing homes. After a time the product was taken off the market because there were numerous incidents of pipes bursting and causing considerable damage. The plastic was found to be not durable and was deteriorating over time. If there is black plastic plumbing piping that is several decades old, it should be replaced.

Low pressure hot water systems

Early hot water systems were typically low pressure, with a header tank installed in the roof space (if there was sufficient height) or mounted on a timber platform on the roof, to provide water pressure (Figure 2).

If the low pressure system is still in use, there is probably insufficient pressure to run modern bathroom fittings such as showers (although some low-pressure shower systems are commercially available).

If renovations are being carried out, the hot water system could be converted to a mains pressure system of which there are numerous options available. The pipework and fittings should be checked for their ability to cope with the additional pressure, and it may be necessary to replace fittings. Mains-pressure systems make for easier water temperature control.

It is unlikely that the original or early low pressure hot water cylinder is still in use, but if so, it is also likely to require replacement. 

Sanitary drainage

If the original sewer drain is still in use it is likely to be in poor condition, displaying cracking or deteriorated joints, and should be replaced. Look for root infiltration from nearby trees.

Uninsulated hot water system

The 2015 BRANZ House Condition Survey, involving over 500 houses, found that two-thirds of hot water pipes were not insulated – this equates to over 1 million houses across New Zealand. Retrofitting insulation to hot water pipes where practicable is a good idea.

Overall, 79% of cylinders that pre-dated 2002 (34% of all cylinders) had no cylinder wrap. This equates to just under half a million houses. The government’s Energy Efficiency and Conservation Authority (EECA) recommends adding a thermal wrap around cylinders manufactured before 2002.

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Who can do what?

Relatively simple plumbing jobs such as connecting up a washing machine or replacing a tap can be done by competent householders, but there are rules around who can do other types of work. Sanitary plumbing – work that involves water supply pipes or waste pipes, traps, ventilation pipes or overflow pipes – must be done by a licensed plumber. You can find more details here.